The invention discloses a method for increasing coal body gas permeability through liquid nitrogen and high-temperature nitrogen gas freeze thawing circulation. Gas extraction drill holes are constructed in a roadway of the working face; magnetized water is injected into the gas extraction drill holes through magnetized water injecting pipes and then seeps into coal bodies around the gas extraction drill holes; the gas extraction drill holes are filled with liquid nitrogen in a liquid nitrogen tank; the liquid nitrogen freezes the magnetized water seeping into the coal bodies and is gasified and converted into nitrogen gas to enable the pressure in the gas extraction drill holes to be increased; the gasified nitrogen gas in the gas extraction drill holes enter a nitrogen gas heating tank to be collected; the nitrogen gas collected in the nitrogen gas heating tank is heated by the nitrogen gas heating tank to enable the high-temperature nitrogen gas to be injected into the gas extraction drill holes, so that the high-temperature nitrogen gas conducts thawing fracturing on the frozen coal bodies; and finally, the steps of coal body freezing and thawing are repeated. According to themethod for increasing the coal body gas permeability through liquid nitrogen and high-temperature nitrogen gas freeze thawing circulation, the coal bodies are frozen firstly, then the frozen coal bodies make contact with the high-temperature nitrogen gas to form a temperature difference effect to conduct the coal body fracturing process, and the permeability-increasing range of the coal bodies canbe effectively increased.